Film substrate, fabrication method thereof, and image display substrate

1. A film substrate fabrication method for fabricating a film substrate, said method comprising: providing a film base material pre-formed with first conductor wiring comprising a semiconductor connection portion to be connected with a semiconductor element and an external connection portion on the film base material to be connected with another panel or substrate, the method subsequently comprising, sequentially: forming a photoresist on the surface of the film base material on which the first conductor wiring is formed; forming an opening and exposing a part of the first conductor wiring by removing the photoresist at a position of the external connection portion on the film base material and a position of the semiconductor connection portion; forming a second conductor wiring by performing metal plating on the first conductor wiring at the opening in the photoresist, whereby the photoresist remains on the surface of the film base material and on the surface of the first conductor wiring, and the surface of the second conductor wiring is exposed through the photoresist left on the surface of the first conductor wiring; and removing a first portion of the photoresist, other than the opening, and leaving a second portion of the photoresist, wherein the second portion of the photoresist is thinner than the first portion of the photoresist, thereby forming an insulating film of a photoresist which is thinner than the thicknesses of the external connection portion on the film base material and the semiconductor connection portion in a region other than the external connection portion on the film base material and the semiconductor connection portion.

2. The film substrate fabrication method according to claim 1 , wherein a reinforcement conductor for film conveyance film holes is disposed on the film base material, and when forming an opening in the photoresist, the position of the reinforcement conductor portion is also opened and a further conductor is formed on the reinforcement conductor portion by performing metal plating.

3. The film substrate fabrication method according to claim 1 , wherein when the first portion of the photoresist is removed, and the second portion of the photoresist is left, the surface of the second conductor wiring of the external connection portion on the film base material and the semiconductor connection portion is formed higher than the surface of the second photoresist portion.

4. The film substrate fabrication method according to claim 1 , wherein a bent portion of the film base material is formed by the first conductor wiring on which the second conductor wiring is not formed.